Thermostatic alarm for bearings



Feb. 6, 1934. R. F. BETHEA THERMOS TATIC ALARM FOR BEARINGS Filed May 9, 1930 5 0.661! {Beth ea ATTORNEY Patented F ch. 6, 1934 UNlTED STATES PATENT ()FFICE 1 Claim.

This invention relates to a thermostatic alarm for machine bearings and other machine parts which are liable to become overheated when not supplied with sufficient lubricant, and the primary object of the present invention is to provide a device of this class which may be readily installed upon any machine part and which will be entirely automatic in its operation.

Another object of the invention is to provide a device of the class described in which the thermostatic element is in the nature of a thermometer and a column of mercury in the tube is taken advantage of as a circuit closing means between two terminals which are associated with the thermometer tube so as to effect closing of the signal circuit when the column of mercury rises above a predetermined degree of temperature.

This invention also consists in certain other features of construction and in the combination and arrangement of the several parts to be hereinafter fully described, illustrated in the accompanying drawing, and specifically pointed out in the appended claim, it being understood of course that minor changes may be made so long as they fall within the scope of the claim.

In describing my invention in detail, reference will be had to the accompanying drawing, wherein like characters denote like or corresponding parts throughout the several views, and in which:-

Figure 1 is a view in front elevation of the thermostatic alarm device embodying the invention.

Figure 2 is a vertical front to rear sectional view taken on the line 2-2 of Figure 1 looking in the direction indicated by the arrows.

Figure 3 is a diametric view illustrating the signal circuit.

The device comprises a metallic frame-like body which is indicated in general by the numeral 1 and which may be of any desired size and shape, and this body includes a top portion 2, side portions 3 and a bottom portion 4, and the last mentioned portion is formed with an opening 5 and, below the opening, with a threaded enlargement 6, of said opening, into which is fitted the threaded upper end of a tubular plug 7 which is exteriorly threaded as indicated by the numeral 8 so as to adapt it to be fitted into a threaded opening in the bearing or other machine part and, for a purpose to be presently explained, this plug is formed, interiorly, with a seat indicated by the numeral 9 which is located near the lower end of the bore 10 of the said plug.

The frame is divided, between its front and rear sides, by a partition plate 11 and mounted upon this plate is a stem 12 of a thermometer, the stem being held in place between two vertical columns of temperature indications, indicated by the numeral 13 by a wire clip 14 which is con- 00 nected at its ends to the partition plate and which embraces the upper portion of the thermometer tube, the bulb of the thermometer, indicated by the numeral 15, resting upon the seat 9 as shown in Figure 2 and being thus positioned in order 66 to be subjected to the heat which is radiated by the machine part in which the plug '7 is fitted.

Binding posts 16 are mounted upon one side of the arm and are insulated therefrom, and short conductor wires 17 are led from these posts "I to the stem 12 of the thermometer and have their ends embedded in said stem at one side thereof as indicated at 18, these ends of the wires being extended so as to be in contact with the column of mercury in the thermometer, and as '5 will be observed by reference to Figures 1 and 2 of the drawing, the wire terminal which is connected with the lower one or" the binding posts 16 is at all times in contact with the mercury column and the other terminal is located in the bore of the thermometer tube at a proper elevation to be contacted by the column of mercury when the temperature of the machine part to which the device is applied has reached a predetermined degree, and therefore this terminal which is led from the upper binding post 16 is located at that point in the height of the thermometer tube opposite which the temperature indication on either scale 13 is located.

The invention contemplates the inclusion, in J0 the electric alarm circuit of a visible as well as an audible signal and with this end in view a block 19 of insulation is mounted upon the rear side of the partition plate 11, and a contact in the form of a leaf spring 20 is mounted at its lower end upon this plug and extends above the same and has its upper end in contact with a contact point of an electric light socket 21.

The lower binding post 16 is preferably not insulated with respect to the frame 1, so that when the column of mercury in the thermometer tube rises to bridge the terminal tubes 18 of the wires 17 and thus closes the circuit from the battery 22, the circuit will be closed through the light bulb socket 21 and also through an electric bell 23 which is in said circuit, and in this manner the visible and audible signals are simultaneously energized in the event of overheating of the hearing or other part in which the plug 7 is fitted, thus giving warning to the 110 engineer or other person who is attending to the machine equipped with the device that lubricant is needed at the point of location of the device. By employing the scale 13 in juxtaposition to the thermometer tube, it is evident that any overheating of the part with which the device is associated may be noted by a glance at the mercury column scale.

What I claim is:-

A thermostatic alarm comprising a metallic frame open at its center and provided at one end with an opening communicating with the central opening, spaced binding posts located at the side of the frame and within the central opening thereof, one of said posts being insulated from the frame, a tubular plug detachably connected with that end of the frame having an opening, said plug having a bore communieating with said opening and said bore being provided with a seat, a thermometer tube having at its end a bulb resting upon the seat of the bore of the plug, said tube extending into the central opening of the frame through the opening at the end thereof, and conductors having terminals embedded in the thermometer tube and connected with the respective binding posts.

ROBERT F. BETHEA. 

